Yarn processing system

ABSTRACT

The invention relates to a yarn processing system, comprising a yarn-feeder (F), a textile machine (M), at least one controlled yarn brake (B) and a tensiometer, which senses the yarn downstream of said yarn brake, for at least measuring the yarn tension (g). According to said invention, the tensiometer (T) is permanently arranged within the yarn path, can be adjusted between a passive position (I) and at least one deflection position (II, III) and can be readjusted from said detection position (II, III) to the passive position (I) after a number of weft cycles, which number suffices to represent at least the proper adjustment of a yarn tension target profile.

FIELD OF THE INVENTION

The invention relates to a yarn processing system allowing highinsertion speeds for different yarn qualities.

BACKGROUND OF THE INVENTION

The yarn tension target profile for the insertion cycles has to beadjusted during the first setting-up or after a changeover of the yarnprocessing system to another yarn quality (style change). A yarn tensiontarget profile is selected which guarantees optimal insertion frequencyand insertion speed with a minimum number of yarn breakages for therespective yarn quality. The yarn tension is influenced by a pluralityof parameters, e.g. the withdrawal tension from the yarn feeding device,the braking effect of the yarn brake, the type and function of theinsertion device of the textile machine, the yarn quality, and the like.

Even characteristics of the yarn like the rubbing property, thediameter, the elasticity, or the density are decisive for the resultingyarn tension profile. Those parameters need certain adjustments e.g. atbraking devices influencing the yarn tension. Deviations from the setyarn tension profile needing compensation may even sometimes occurduring operation of the yarn processing system, e.g. caused by differentdiameters of the supply bobbins, fluctuating yarn characteristics anddifferently spooled supply bobbins. The textile machine ought to processthe yarn as quickly as possible for obvious reasons. In case of weakyarns the strength of the yarn sets a limit. If then the machine speedis raised beyond a critical limit the number of yarn breakages increasesexponentially. The highest tension peaks caused by the high insertionspeed may be reduced by means of a controlled yarn brake such that thetension remains close to lower values during particularly criticalphases of the insertion. For this purpose high grade controllable andadjustable yarn brakes already exist. The precise setting of those yarnbrakes is complicated such that they gained only limited positiveinfluences on the processing efficiency in the yarn processing system inpractice. Controlled yarn brakes can be adjusted optimally only with theinformation of the actual tension or the actual tension profile,respectively, during an insertion cycle. The information on the yarntension can be obtained with the help of the tensiometer. Thetensiometer, however, means an additional yarn friction angle during themeasurement of the yarn tension. This additional friction angle, causedby the tensiometer, may mean a catastrophe for weak yarns, because theadditional tension generated by the tensiometer increases the likelihoodof yarn breakages dramatically such that the tensiometer cannot be usedfor a continuous operation of the yarn processing system with weakyarns. In the setting phase and until an optimal yarn tension targetprofile is adjusted this disadvantageous influence of the tensiometer onweak yarns, however, can be tolerated. Stronger yarns, which areprocessed with the help of a controlled yarn brake, to the contrary, canstand the detrimental influence of the tensiometer without an increaseof the likelihood of yarn breakages even during constant operation.

It is known to employ a portable tensiometer which is put in the yarnpath, measures the yarn tension, and, in some cases, shows the yarntension on a laptop. The tensiometer is used for a number of insertioncycles which is representative of the adjustment of the yarn tensiontarget profile, in order to adjust e.g. the withdrawal tension at theyarn feeding device, the braking level or timing of the yarn brake, andthe like. During this adjustment phase yarn breakages or otherdisturbances may occur to a certain extent, until finally the optimalyarn tension target profile is found and established.

A yarn processing system known from EP 0 357 975A (corresponding to U.S.Pat. No. 5,050,648) employs a controlled yarn brake which is operatedwith the help of a tensiometer which is placed permanently in the yarnpath. The tensiometer, permanently operating in its detection positionwould allow to adjust an optimal yarn tension target profile, however,the influence of the tensiometer is a drawback for weak yarn qualitiesbecause of the additional yarn deflection and yarn friction.

EP 0 605 550 A (corresponding to U.S. Pat. No. 5,462,094) discloses ayarn processing system having a tensiometer which is permanentlyassociated to a controlled yarn brake and which is adjustable between apassive position and a detection position. Since the tensiometer isadjusted to the detection position only temporarily during eachinsertion cycle, namely when simultaneously the yarn brake is operating,no information on the yarn tension is available when the yarn brake doesnot brake. So to speak, the tensiometer only is able to measure arestricted section of the yarn tension profile during an insertioncycle. For an adjustment of an optimal yarn tension target profile,however, both the development and the course of the yarn tension duringthe entire insertion cycle are needed.

It is an object of the invention to provide a yarn processing system asdisclosed at the beginning which allows high insertion speeds fordifferent yarn qualities and with a minimal yarn breakage quota only.

Said object can be achieved by a yarn processing system comprising atleast one yarn feeding device associated to a yarn channel, a textilemachine like a weaving machine or a knitting machine, a yarn brake inthe yarn path between the yarn feeding device and the textile machine,which yarn brake at least is adjustable, and a tensiometer at least formeasuring the yarn tension, which tensiometer scans the yarn downstreamof the yarn brake, which tensiometer is provided permanently in the yarnpath and is switchable between a passive position and at least onedetection position, and which tensiometer can be selectively switchedfrom the respective detection position into the passive position after anumber of insertion cycles has occurred which number is representativeat least for the adjustment of a yarn tension target profile.

As soon as the tensiometer is switched over to the detection position,the tensiometer monitors the development and the course of the yarntension during the entire insertion cycle. The tensiometer remains inthe detection position for a representative number of insertion cycles,typically for about 50 to 100 insertion cycles, until the optimal yarntension target profile is adjusted by varying the parameters influencingthe yarn tension. The optimal yarn tension target profile is a targetprofile which assures a minimum number of yarn breakages in case ofoptimal high insertion speeds. In case of strong yarn qualities thetensiometer may remain in the detection position after the adjustment,in order further on to provide permanent information on the yarntension, because strong yarn qualities can stand the additional frictioncaused by the tensiometer. However, as the tensiometer selectively canbe readjusted to the passive position, an optimal yarn tension targetprofile can be adjusted even for weak yarn qualities, in some casesfirst with disturbances caused by the tensiometer. The finally foundyarn tension target profile guarantees a minimal yarn breakage quota foran optimal high insertion speed, however, and after the tensiometer hasbeen switched back to the passive position. The short period of timeduring which the weak yarn has to stand the additional friction does notmean a significant reduction of the efficiency of the textile machine.In the case that for strong yarn qualities the tensiometer is maintainedin the detection position, even during constant operation newadjustments of the parameters may be carried out, e.g. at the controlledyarn brake, when e.g. the quota of yarn breakages should have increasedas a consequence of the above-described influences. In case of anon-controlled yarn brake the tension measured by the tensiometer in thedetection position may be used with the help of graphical or numericaldisplays to manually adapt the braking level of the yarn brake.

The switchable tensiometer, expediently, is associated to a yarn brakeoperating with an adjustable braking level which remains unchangedduring the insertion cycle, in order to vary the braking level until anoptimal yarn tension target profile could be found, or is associated toa controlled yarn brake, respectively, which allows to vary the brakingeffect during one and the same insertion cycle. The timing and/or thebraking level of the controlled yarn brake can be adjusted with the helpof the information from the tensiometer.

The tensiometer, advantageously, is directly connected to an adjustmentdevice of the yarn brake such that it may operate in a closed regulationloop with feedback. In this case a computerised control device orbraking level adjustment device of the yarn brake are expedient whichresponds to the measured yarn tension in some cases in a correctingfashion.

In a simple embodiment the tensiometer or at least the tensiometerelement which actuates the yarn during a measurement can be switchedmanually or mechanically. A manual switching operation may be carriedout by directly engaging at the tensiometer or the element respectively.A mechanical switch over e.g. can be carried out with the help of aspring which automatically adjusts the tensiometer into the passiveposition after the representative number of insertion cycles has passed.

The tensiometer or the element engaging on the yarn, respectively,expediently is connected with a switch over actuator, preferably anelectromagnet or an electric motor which receives the command, e.g. froma timer or a program, to adjust the passive position of the tensiometerafter the representative number of insertion cycles had passed.

The handling is very comfortable if the tensiometer is provided with adisplay device for the measurement results, preferably a display devicewith a graphical or numerical indication.

Since the tensiometer is permanently provided in the yarn path it isexpediently connected to the operation panel of the textile machine suchthat the tensiometer cannot only be switched over from the operationpanel but such that the measurement results can be displayed and in somecases even recorded on the operation panel. In such cases it isexpedient if the display already provided on the operation panel alsocan be used to display the measured yarn tension.

It is expedient to connect the tensiometer to an automatic switch overcontrol device which takes care, e.g. after the representative number ofinsertion cycles has occurred, that the tensiometer is switched over tothe passive position, and which also takes care that the tensiometer isbrought in to the respective correct detection position.

In order to minimise the influence of the tensiometer in the detectionposition for the yarn the tensiometer is structurally combined with theyarn brake, preferably such that the tensiometer uses at least one yarndeflection location of the yarn brake for the measurement.

The tensiometer even may be provided upstream or downstream of a yarndetector, preferably of a weft yarn detector of a weaving machine, and,expediently, even may be structurally combined with the weft yarndetector, preferably such that the tensiometer uses at least one yarndeflection location of the weft yarn detector for the measurement.

Particularly expedient, the tensiometer can be switched into severaldifferent detection positions, e.g. depending on the respective yarnquality, which differ from each other e.g. by the respective yarndeflection angle. This is because heavy yarn qualities may need asmaller friction angle for a correct tension measurement than light yarnqualities.

In order to achieve correct measurements despite the different detectionpositions, it is expedient to provide an electronic measurementevaluation device comprising an automatic compensation circuitry for thedifferent detection positions in order to compensate for the thendiffering parameters. For the respective detection position at least oneposition sensor ought to be provided which is connected to theevaluation device. There are namely different force triangles during themeasurements in the different detection positions. Those different forcetriangles would influence the measuring parameters and could falsify themeasurements, respectively. The evaluation electronics, however, areable to select the respective correct parameters with the help of theinformation from the position sensor in order to guarantee correctmeasurements independent from the respective detection position.

In the case that the yarn processing comprises several yarn channelseach of which is supplied by at least one yarn feeding device,expediently one tensiometer is permanently provided in each yarn channelsuch that it can be switched over, in order to allow the adjustment ofthe same optimal yarn tension profile for each yarn channel, or even insome cases to adjust an individual optimal yarn tension profile in eachyarn channel, respectively.

The invention is applicable to all kinds of weaving machines andknitting machines. A yarn processing system, however, is preferred thetextile machine of which is a rapier weaving machine or a projectileweaving machine, although even a jet weaving machine could be provided.In case of knitting machines different machine types could be used likecircular knitting machines or flat knitting machines, or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the object of the invention will be explained with thehelp of the drawing in which:

FIG. 1 is a schematic side view of a yarn processing system including aweaving machine,

FIG. 2 is a detail as a variant to FIG. 1,

FIG. 3 is a further detail as a variant to FIG. 1,

FIG. 4 is a detail as a further variant to FIG. 1, and

FIG. 5 is a yarn tension target profile.

DETAILED DESCRIPTION

A yarn processing system S shown in FIG. 1 comprises at least one yarnfeeding device F which is associated to a channel Kl of a textilemachine M and which supplies the textile machine M with a yarn Y. Theyarn Y is taken from a yarn bobbin L, is intermediately stored on astorage body 1 of the yarn feeding device F, and is inserted along ayarn path by an insertion device E into the textile machine M. Thetextile machine M shown in FIG. 1 is a weaving machine, in particular aprojectile weaving machine or a rapier weaving machine, however, butalso could be a jet weaving machine. Alternatively, the textile machineeven could be a knitting machine.

In the case of a weaving machine as the textile machine M, a yarn brakeB, downstream thereof permanently a tensiometer T, downstream thereof insome cases a weft yarn detector D and subsequently the insertion deviceE are provided in the yarn path downstream of the yarn feeding device F.The yarn Y is inserted into a weaving shed 8 intermittently in insertioncycles determined by a control device CU of the weaving machine by theinsertion device E and then is respectively beaten up by a not shownreed. An operation panel having a display G is not shown in detail butbelongs to the control device CU of the weaving machine.

In the case of a projectile weaving machine or a rapier weaving machinea withdrawal brake 2 is associated to the storage body 1 of the yarnfeeding device F which withdrawal brake 2 generates a predeterminedrelatively constant basic tension in the yarn Y during withdrawal. Inthe case of a jet weaving machine no withdrawal brake 2 is provided, butinstead a not shown stopping device which provides the lengthmeasurement of the weft yarn.

The yarn brake B includes an adjustment device 3 for adjusting thebraking level (the braking force), in order to generate during thewithdrawal operation a desired yarn tension in the yarn Y between theinsertion device E and the yarn brake B. In some cases stationary yarnguiding elements 5 may be provided at the yarn brake B.

FIG. 1 shows in dotted lines a possible alternative of a controlled yarnbrake B having a control device 4. This means that the control yarnbrake B is activated and deactivated during each insertion cycle by thecontrol device CU, e.g. depending on control signals, in order to varythe braking effect during one and the same insertion cycle and/or toswitch between phases with a braking effect and without a brakingeffect, respectively.

The weft yarn detector D monitors the movement of the withdrawn yarn Yand emits a disturbance signal in the case that in a phase no movementis detected during which phase a movement of the yarn Y is to beexpected.

In the case of a rapier weaving machine or a projectile weaving machinethe insertion device E includes a yarn selector which selects therespective yarn Y which is to be inserted from one of in some casesseveral yarn channels and brings the selected yarn to the insertionelement which then inserts the yarn into the weaving shed 8, before theyarn is beaten up by the reed and is cut. In the case of a rapierweaving machine the yarn is taken by a bringer gripper at the insertionside end of the weaving shed and then is transported to about the middleof the weaving shed 8, is then transferred to a taker gripper andfinally is brought by the taker gripper completely through the weavingshed 8. In a projectile weaving machine a projectile is shot throughwith each weft yarn. In the case of a jet weaving machine the insertiondevice E includes at least one main nozzle and in some cases additionalnozzles in the weaving shed 8 in order to insert the yarn Y with thehelp of air jets.

The yarn processing system S is provided with the permanently installedtensiometer T downstream of the yarn brake B. The tensiometer T (or theelement P of the tensiometer engaging at the yarn Y) can be switchedover between a passive position (in dotted lines) and at least onedetection position (in full lines). There is no engagement at the yarnin the passive position. In the detection position the yarn Y isactuated with a deflection and with friction in order to measure theyarn tension. The deflection, e.g., is carried out in relation to thestationary yarn guiding elements 5. The switch over movement isindicated by a double arrow 6. The tensiometer T has an indicator 7 forthe measured tension. The yarn tension may be displaced graphically ornumerically. Dotted lines indicate that the tensiometer T is connectedwith the control device CU or the operation panel of the textilemachine, respectively. In the latter case, the display G also can beused to indicate the measured tension. Even the setting devices (akeyboard) in the operation panel may be used in order to actuate thetensiometer and to adjust the tensiometer in some cases, respectively.

The tensiometer T may be provided at one of different positions, asindicated by the arrows a, b and c.

The tensiometer T is used to adjust or establish an optimal yarn tensiontarget profile for the insertion cycles (a tension curve over oneinsertion cycle), which assures the lowest quota of yarn breakages foran optimally high insertion speed in the textile machine.

The yarn tension target profile is shown in FIG. 5 schematically for theexample of a rapier weaving machine. The adjustment of a yarn tensiontarget profile inter alia is carried out in case of the first operationor after a change of the processed yarn quality or when the quota ofyarn breakages should have increased during operation of the yarnprocessing system, respectively. The adjustment can be carried outmanually at components of the yarn processing system which are decisivefor the yarn tension, or even automatically within at least one closedregulation loop with feedback. For an adjustment with the tensiometerbrought in to the detection position a sequence of insertions is carriedout, typically 50 to 100 insertions, in order to adjust the parameterswhich influence the yarn tension profile. In the case of a strong yarn Ythe tensiometer T remains in the detection position after the adjustmenthas been carried out. The tensiometer then may in some cases be usedfurther on for the control of the controlled yarn brake B and the like.In the case of weak or delicate yarn material the tensiometer T isswitched over to the passive position after the adjustment phase suchthat the tensiometer does not further on have any influence on the yarnY. The options to selectively bring the tensiometer or the element P ofthe tensiometer which acts upon the yarn, respectively, in to thepassive position, in case that this is expedient for the processed yarnmaterial, or, to the contrary, to maintain the tensiometer in thedetection position if the yarn material can stand the additionalfriction and the deflection by the tensiometer, are an essential featureof the tensiometer T which per se is permanently provided in the yarnpath. In the case that there are several yarn channels at the textilemachine M a tensiometer is provided in each yarn channel and such thatit can be switched over between a passive position and at least onedetection position.

FIG. 2 shows a manually switchable tensiometer T the element P of whichengages at the yarn is supported adjustably in a guide 9 and isadjustable back and forth between stops 10 defining the passive positionI and one detection position II. A handle 11 e.g. is provided for theswitching operation which allows to carry out the adjustments manuallyby being pivoted in the direction of the double arrow 6. As a not shownalternative the tensiometer may be loaded by a spring in a directiontowards the passive position and may be held by a detent mechanism inthe detection position. A not shown control device, e.g. a timer or aprogram, releases the detent mechanism after the representative numberof insertion cycles needed for the adjustment such that the tensiometerT then automatically is switched over to the passive position.

The tensiometer T shown in FIG. 3 is connected to an actuator A whichcarries out the switch over movements (double arrow 6). The actuator maybe an electromagnet or an electric motor. The tensiometer T in FIG. 3 orthe element P engaging on the yarn, respectively, does not have a singledetection position II, but has at least one further detection positionIII. Different yarn deflection angles result in both detection positionsII and III. The actuator A may be controlled from an operation panel ofthe weaving machine in order to adjust the selected detection position,or may be controlled directly at the tensiometer T, respectively, inorder to switch the tensiometer T, e.g., back to the passive position I.A timer or a program may be provided which take care of the switch overaction after the representative number of insertion cycles has beencarried out.

FIG. 3 shows a control unit C of the tensiometer T in which anevaluation device for the measurement result (computerised circuitryincluding a microprocessor) is contained and in some cases, acompensating device 12 for the consideration of the differing forcetriangles occurring in the different detection positions II and III andto gain respective correct measurement results despite the differingforce triangles. The control unit C of the tensiometer may be connectedwith at least one position sensor 13 which detects the respectivelytaken detection position II or III and which informs the control deviceC correspondingly for a compensation.

In order to produce as little additional friction and deflection aspossible in the yarn, the tensiometer T may be structurally combinedwith the yarn brake B or the detector D, respectively. In FIG. 4, e.g.,the tensiometer T uses a yarn guiding element 14 of the weft yarndetector D as a stationary deflection location relative to the elementP. The yarn guiding element 14 e.g. is a piezoelectric elementresponding to the yarn motion. A similar structural combination insteadcould also be provided with the yarn guiding element 5 downstream of theyarn brake B.

A typical yarn tension profile (similar to a heart curve) results fromthe operation of a rapier weaving machine. FIG. 5 illustrates the yarntension (in grams g) during an insertion cycle (rotational angle of themain shaft of the weaving machines). The yarn has a predetermined basictension, generated by the withdrawal brake 2 and by the yarn brake B (inthe case that the latter is not a controlled yarn brake but has a basicadjustment of the braking level). After the yarn is taken by the bringergripper a first relatively sharp rise 16 results in the curve 15. In thesubsequent acceleration phase of the bringer gripper the yarn tensionrises in the curved part 17 before the yarn tension again is reducedshortly prior to the transfer phase in the middle of the weaving shedduring the deceleration of the bringer gripper. At this time (curve part18) a predetermined yarn tension is obtained with which the yarn istransferred to the taker gripper. This yarn tension is important inorder to assure a correct transfer. Subsequently the taker gripperaccelerates such that again a curved part 17 with increasing yarntension occurs, before the yarn tension drops with the deceleration ofthe taker gripper to a curved part 19. The tension variations shown at19 result from the beat up movement of the reed and the cutting of theyarn. It is important for the curve which is adjusted during theadjustment procedure that the curve parts 17 are relatively mild andthat a certain tension development is achieved with a predeterminedbasic tension in the curved part 18.

In the detection position the tensiometer T measures the yarn tensiondownstream of the yarn brake B. Then, with the help of the measurementresult or the measurement results of the representative number ofinsertion cycles, respectively, the withdrawal brake 2 and the yarnbrake B, and in some cases, the detector D can be set so that theoptimal curve 15 of FIG. 5 results. Those adjustments can be carried outmanually or in a closed regulation loop by means of automatic regulatingdevices which are not shown in detail, e.g. guided by the control deviceC and/or the control device CU. In this fashion the curve 15 isestablished. As soon as this has been done the yarn processing systemmay start the normal operation. In the case of a strong yarn which doesnot have a tendency to break despite the engagement of the tensiometer,the tensiometer T is kept in the detection position. This allows tomonitor the normal operation with the help of measurement results and tocarry out, in some cases, further adjustments or optimisations. In thecase of a weak yarn, however, the tensiometer T then is switched over tothe passive position in order not to influence the yarn further on. Ifnecessary, in case of the occurrence of irregularities or when the quotaof yarn breakages increases, or even regularly only for “checkingpurposes”, e.g. with each 100000^(th) insertion, the tensiometer T thenmay be switched over in to the or into one detection position,respectively, in order to then carry out re-adjustments.

The shown tensiometer operates according to the principle of yarndeflection by the element P which is adjusted laterally to the yarnrunning path and relative to two stationary deflection locations 5.However, also other types of tensiometers may be used, e.g. comprising apiezoelectric element or a pivotable element P. The indicator 7 may beprovided directly at the tensiometer. However, alternatively, only theindicator on the display G of the operation panel of the weaving machinecould be used, or even both indicators.

For the adjustments e.g. of the withdrawal brake 2 or the yarn brake B,respectively (in some cases also of the detector D), auxiliary devicescould be provided which are not shown in detail and which are designedto carry out the adjustments automatically in a closed regulation loop,guided by the measurement result of the tensiometer T.

Although a particular preferred embodiment of the invention has beendisclosed in detail for illustrative purposes, it will be recognizedthat variations or modifications of the disclosed apparatus, includingthe rearrangement of parts, lie within the scope of the presentinvention.

1. Yarn processing systems, comprising at least one yarn feeding deviceassociated to a yarn channel, a textile machine like a weaving machineor a knitting machine, a yarn brake in the yarn path between the yarnfeeding device and the textile machine which yarn brake at least isadjustable, and a tensiometer at least for measuring the yarn tensions,which tensiometer scans the yarn downstream of the yarn brake, whereinthe tensiometer is provided permanently in the yarn path and isswitchable between a passive position and at least one detectionposition, and wherein the tensiometer selectively can be switched fromthe respective detection position in to the passive position after anumber of insertion cycles has occurred which number is representativeat least for the adjustment of a yarn tension target profile.
 2. Yarnprocessing system as in claim 1, wherein the switchable tensiometer isassociated either to a yarn brake which has a constant but adjustablebraking level during the insertion cycle, or to a yarn brake the brakinglevel of which is controllable during the insertion cycle, respectively.3. Yarn processing system as in claim 1, wherein the tensiometer isconnected to an adjustment device, preferably to a computerised controldevice or braking level adjustment device of the yarn brake.
 4. Yarnprocessing system as in claim 1, wherein the tensiometer or at least anelement of the tensiometer which engages at the yarn during ameasurement is manually or mechanically switchable.
 5. Yarn processingsystem as in claim 1, wherein the tensiometer or at least an element ofthe tensiometer which engages at the yarn during the measurement isconnected to a switching actuator, preferably to an electromagnet or toan electric motor, respectively.
 6. Yarn processing system as in claim1, wherein the tensiometer is provided with an indication device for themeasurement result or the measurement results, respectively, preferablyan indication device producing a graphical and/or numerical depiction.7. Yarn processing system as in claim 1, wherein the tensiometer isconnected with the operation panel of the textile machine, preferablyalso to a display provided on the operation panel.
 8. Yarn processingsystem as in claim 1, wherein the tensiometer is connected to anautomatic switch over control device, in which, preferably, a timer or aprogram is provided for the duration of the adjustment of the detectionposition.
 9. Yarn processing system as in claim 1, wherein thetensiometer is structurally combined with the yarn brake, preferably byusing at least one yarn deflection location of the yarn brake for themeasurement.
 10. Yarn processing system as in claim 1, wherein thetensiometer is arranged upstream or downstream of a yarn detector,preferably of a weft yarn detector of a weaving machine.
 11. Yarnprocessing system as in claim 10, wherein the tensiometer isstructurally combined with the weft yarn detector, preferably for usingat least one yarn deflection location of the weft yarn detector for themeasurement.
 12. Yarn processing system as in claim 1, wherein thetensiometer is switchable into several, different, e.g. yarn qualitydepending, detection positions, which differ, preferably, by theirrespective yarn deflection angles.
 13. Yarn processing system as inclaim 12, wherein an electric measurement evaluation device is providedfor the tensiometer, preferably comprising an automatic compensationcircuitry for measurement parameters associated to the differentdetection positions, that at least one position sensor is provided forthe respective detection position of the tensiometer or of the elementof the tensiometer which engages at the yarn during the measurement, andthat the position sensor is connected to the evaluation device.
 14. Yarnprocessing system as in claim 1, wherein several yarn channels areprovided, each being supplied with yarn by at least one yarn feedingdevice, and that a tensiometer is provided in each yarn channel.